PCMusicGuy

Never hesitate to share your knowledge. I'm no Z06 exhaust groupie but I definitely understand what you are saying. The A/F curve does make all the difference. But it is nice to see uncorrected real world results and really illustrates just how sensitive the A/F curve is to small modifications. You can bet your sweet kisser that an aftermarket company would market the example above as 20HP and 15 TQ. (K&N comes to mind )

#1 TA WS-6

Thanks for clearing that up for me lightning. The purpose of the zo6 exhaust was to keep the warranty and it was extremely cheap. As soon as warranty is out LTs will be going in.

#1 TA WS-6

BTW guys. This was not to be an end all result to this mod for EVERY car out there. I am just sharing the results as they came. I completly dissagree that this was not a good test or comparison. There are 2 ways to think about it. Without a tune before and after and with a tune before and after. Generaly when you see tests like this there is only one independent variable and one dependent variable. The mod being the independent var and power is dependent var. In my test there were 2 dependent variables, tune and power since the tune was not contolled for. This is not as good but Im not going to tune the car just for ZO6 exhaust. There could have been any number of interaction effects between the 2 dependent variables like spin said.

The tune will come along after a few more mods. I will continue to post all results from every modification. Looking forward to that ported manifold!

///DarkSide\\\

So...unless you want to tune the car, to be safe, stay away from headers (Z06 or other).

When I do tune the car, ~2013 seams so far away , a Z06 exhaust plus tune on a CA car seems to be the best option.

Ragtop 99

That is incorrect. In your test there is still only one independent variable, the exhaust, and one dependent variable, HP. The tune could be a second independent variable, but it is not controlled for in your data. It can not be a second dependent variable. Since it is well known that the tune has an effect and yet was not controlled for, you wind up with the possibility of autocorrelation in your results that results from A/F not being controlled.

Bottom line is for those that will get a tune, but want to pass visual inspection, it is not a valid data point. Your test is a valid data point for those that might do the mod and not get a tune. Since there are some out there that might do this for warranty issues, it was good to post this.

vetracer

The LS7 manifolds are also going to be as quiet as the stock LS3 manifolds, another reason I liked them for my street driven coupe. Besides, they were already paid for along with all the other donor parts I took off my Z

SpinMonster

I think you have it nailed that a tune will void your warranty and thats not true. Ask your dealer if they will have an issue with it and if so locate a dealer who doesnt have an issue with it or possibly one that tunes the car with a custom calibration.

Many tuners did this. My dealer for example installed headers, CAI, gears, and the mag supercharger and honored the factory warranty. They exist.

That aside, most guys run the car with a tune and dont mention it. The tech 2 CANNOT detect that it was tuned. It simply writes the factory calibration over whats in there. The rumor was started with a lie and keeps so many guys driving the car pig rich. You are damaging the car running it long term pig rich with oil getting into the combustion chamber. My Hummer has a custom HPtuners tune and was in 3 times for factory service and it wasnt detected even with the tech 2 being used to find a fault with a heated seat.

#1 TA WS-6

I fail to see how the tune could have changed by some other variable than the mod. The tune WAS controlled for. There was no tune. Its either there was a tune or not. If you get a tune then this info will not help you. If you dont, it MIGHT provide some information. If you will notice I did not say hp. I said power in general.(hp and tq) The tune is controlled for because there is a tune or there isnt one. (obviously i am excluding differences in tunning) The tune is dependent because I did not control it directly.

With no outside help other than the exhaust it is ABSOLUTLY clear there were ATLEAST 2 dependent variables. Power and A/F both changed by a single mod. I am sure there is a cooerelation between the 2 but it is still true that with the exhaust there was a change in both and is not proportional.



Of course I have been drinking! lol

Ragtop 99

A/F is not a dependent variable. The object of mods is to maximize HP, so HP is the dependent variable. A/F is an another independent variable that can be manipulated to achieve that. HP is a function of A/F and is highly correlated; correlation need not be linear.

We agree on the conclusion, so we're only talking experimental design at this point.

///DarkSide\\\

I agree that problems w/ heated seats, etc. wouldn't be an issue, that's not where my concern lies, my worry is: the trans takes a dump or the timing chain breaks etc. Worst-case scenario stuff, aka big $$$ to fix stuff, to where they would look for a tune after seeing the other "visible" mods.

Yes, I could ask the dealer if they're tune friendly, but a verbal "don't worry" ain't worth sheet in this world.

SpinMonster

When they check for things like heated seats, they hook up the Tech 2 which reflashes the tune to stock. The hummer was tuned and the Tech 2 didnt detect the tune because IT CANT. He updated the tune with the latest OS and I was on my way. I put my tune back in right away.

GM cant delete part of your warranty. Its either all or none. If the car has mods, and my nitrous bottle sitting just behind the seats open and visible, its a sure thing they know A-the car is modded and B-the nitrous system is wired into the electrical system. I had this done for both my Hummer and Corvette and neither car with a tune from day 1 was voided on the warranty.

I was at the dealership with RacerX as he had his trans tune reloaded under warranty as we explained that flashing the computer caused strange operating characteristics. He tipped all involved and drove his H/C car home fixed under warranty.

If you mod, you dont deserve warranty repair and 'hiding mods' to have GM fix what it wasnt designed to have is still stealing. I mod and dont care if its voids a warranty because I wouldnt let them wrench on my car from the day I buy it.

Finding a dealer that does the mods would be what guys like you should do. They will honor the warranty on what they did. Better yet, find a tuner that does warranty work and have him do everything.

SpinMonster

Its one way to deal with varying opinions...

#1 TA WS-6

the point of this mod was not max hp. Lts are used to maximize power

#1 TA WS-6

the point of this mod was not max hp. Lts are used to maximize power


I do agree that the exp design could change btn both though.

rednred

quick question/clarification ... you say ...
First I tried to reuse the ls3 gaskets. There was a noticeable exhaust leak. You must use the ls7 gaskets.

Which gaskets? head to manifold or manifold to converter/down pipe?

getting ready to do this and went ahead with manifold to converter but would like to pre-purchase head to manifold if needed.

Thanks.

#1 TA WS-6

I was talking about the head to manifold gasket. The cats are not interchangeble. I hope the install goes well for you!

rednred

Thanks! It'll go - time will tell how

ZishanM

Actually I think it proves the exact opposite. If the he made 20HP and 15 TQ with the same Air Fuel Ratio as before, then we could attribute the power increase to the headers, but in fact the power he made is because the air fuel ratio leaned itself out and not because of the headers.

All the headers did was help him to lean the car out without a tune, I think he could have made the same horsepower without the headers and just with a tune. There is no two ways around it, leaning the car out makes power.

I really appreciate the effort members are putting fourth in trying to get to the bottom of this, but there has to be a control. The AFR has to be at a set level. I would think that if the car was tuned first to a certain AFR first, and then the headers were added, and matched to the same AFR, THEN we would finally have an apples to apples comparison on how much power the headers add.

I think the headers make a difference the only question is how much and where in the horsepower curve.

#1 TA WS-6

Once again I would like to point out that I did this just to show what the exhaust did on its own. NOT what a tune and exhaust would do. I think with a tune another 5-10hp is not out of the question. This mod had an effect on more than one aspect of the car. It just so happens it was a good change. I think for the $ I have in this setup it was def worth it.

OliverM5

I'm have a full Z06 exhaust (headers to tailpipe) for sale:

http://forums.corvetteforum.com/c6-p...-tailpipe.html